Scope: Enzymatically modified rice starch (ERS) synthesized with 4-α-glucanotransferase has a longer structure than rice starch, which could delay digestion, similar to dietary fiber. We investigated the effects of ERS on glucose and lipid metabolism with mice fed a high-fat diet containing ERS (HFD-ERS).
Method and results: Four weeks of ERS feeding showed hypoglycemic effects with a significant reduction in fasting glucose (46%), insulin (57%), and leptin (83%) levels; improved glucose tolerance (20% in AUC of oral glucose tolerance test); and increased adiponectin concentrations (+27%) compared to the HFD group. Notably, phosphorylation of AMP kinase (AMPK) was markedly induced in the HFD-ERS livers compared to HFD livers. Additionally, ERS significantly reduced total cholesterol concentrations with induction of fecal bile acid excretion (+21%, P<0.05) in the HFD-ERS group compared to the HFD group. The mRNA and protein expressions of hepatic LDL receptors were significantly induced. However, cholesterol 7 alpha-hydroxylase (CYP7A1) expression was downregulated possibly due to induction of intestinal farnesoid X receptor (FXR; +2.4-fold, p<0.05) and fibroblast growth factor-15 (FGF-15; +2.2-fold, p<0.01).
Conclusion: Our data suggest that ERS feeding may have hypoglycemic and hypocholesterolemic effects via a mechanism similar to that of dietary fiber.
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